topnotch_website/database/factories/InvoiceFactory.php

<?php

namespace Database\Factories;

use App\Models\Customer;
use App\Models\Invoice;
use Illuminate\Database\Eloquent\Factories\Factory;
use Illuminate\Support\Carbon;

class InvoiceFactory extends Factory
{
    protected $model = Invoice::class;

    public function definition(): array
    {
        $customer = Customer::all()->shuffle()->first();

        return [
            'created_at'  => Carbon::now(),
            'gst'         => true,
            'pst'         => $this->faker->boolean(25),
            'paid'        => $this->faker->boolean(),
            'customer_id' => $customer->id,
            'updated_at'  => Carbon::now(),
        ];
    }
}